Solid-electrolyte interphase (SEI) layers are formed by reduction (oxidation) of solvents and salts at the surface of anodes (cathodes) of Li-ion batteries.  Depending on the chemistry, composite inorganic-organic SEI layers may exert more or less protective roles on the electrode structure.  Current research targets characterization of SEI layer structure and composition, and development of stabilizer electrolyte additives.  Additional focus is on SEI dynamical evolution during battery cycling and effects on capacity fading. Theoretical/computational methods based on static density functional theory and ab initio molecular dynamics simulations contribute significantly to the understanding of mechanisms and interpretation of experiments and materials design. We discuss our efforts to elucidate the surface reactions occurring during SEI layer nucleation and growth. In particular, we address the formation of SEI layers on lithiated silicon anodes as a function of the degree of lithiation and of the nature of the electrolyte. We first analyze the reduction of one of the main solvents: ethylene carbonate (EC) and its mixtures with a linear solvent, diethylene carbonate (DEC), and then those of the most common additives (vinylene carbonate, VC and fluoroethylene carbonate, FEC) on the surface of lithiated SixLiy surfaces.  Also we investigate aggregation of the main products and subproducts and possible secondary reactions.

Modeling solid-electrolyte interfacial reactions on Si anodes of Li-ion batteries

248th National Meeting (2014)

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